Group III nitride compound semiconductor device

Abstract

Aluminum gallium nitride (Al x Ga 1−x N, 0<x<1) is employed as a substrate of a Group III nitride compound semiconductor device. In light-emitting diodes and laser diodes employing the substrate, crack generation is prevented, even when a thick cladding layer formed of aluminum gallium nitride (Al x Ga 1−x N, 0<x<1) is stacked on the substrate. The smaller the difference in Al compositional proportion between the substrate and an aluminum gallium nitride (Al x Ga 1−x N, 0<x<1) layer, the less likely the occurrence of crack generation.

What is claimed is:  
     
       1. A Group III nitride compound semiconductor device comprising a substrate and one or more Group III nitride compound semiconductor layers on first and second surfaces of the substrate, wherein aluminum gallium nitride satisfying the formula (Al x Ga 1−x N, 0<x<1) is employed as the substrate. 
     
     
       2. A Group III nitride compound semiconductor device according to  claim 1 , wherein among the Group III nitride compound semiconductor layers stacked on the first and second surfaces of the substrate, all layers having a thickness of more than 10 nm are independently formed of a compound represented Al x Ga 1−x N, wherein 0≦x≦1. 
     
     
       3. A Group III nitride compound semiconductor device according to  claim 2 , wherein each of the one or more Group III nitride compound semiconductor layers stacked on the first and second surfaces of the substrate is formed of a compound represented by Al x Ga 1−x N, wherein 0≦x≦1. 
     
     
       4. A Group III nitride compound semiconductor device according to  claim 2 , wherein a first layer of the Group III nitride compound semiconductor layers stacked on the first and second surfaces of the substrate has a thickness of 1-20 μm. 
     
     
       5. A Group III nitride compound semiconductor device according to  claim 1 , wherein each of the one or more Group III nitride compound semiconductor layers stacked on the first and second surfaces of the substrate is formed of a compound represented by Al x Ga 1−x N, wherein 0≦x≦1. 
     
     
       6. A Group III nitride compound semiconductor device according to  claim 1 , wherein a first layer of the one or more Group III nitride compound semiconductor layers stacked on the first and second surfaces of the substrate has a thickness of 1-20 μm. 
     
     
       7. A Group III nitride compound semiconductor device according to  claim 1 , wherein a first layer of the one or more Group III nitride compound semiconductor layers stacked on the first and second surfaces of the substrate has a thickness of 2-10 μm. 
     
     
       8. A Group III nitride compound semiconductor device comprising a substrate and one or more Group III nitride compound semiconductor layers on a first surface or first and second surfaces of the substrate, wherein aluminum gallium nitride (Al x1 Ga 1−x1 N, 0<x 1 <1) is employed as the substrate and aluminum gallium nitride (Al x Ga 1−x N, 0<x<1) is employed as the at least one layer in said Group III nitride compound semiconductor layers and further wherein x 1  is equal or nearly equal to x. 
     
     
       9. A Group III nitride compound semiconductor device according to  claim 8 , wherein among the Group III nitride compound semiconductor layers stacked on the first surface or first and second surfaces of the substrate, all layers having a thickness of more than 10 nm are independently formed of a compound represented by Al x Ga 1−x N, wherein 0≦x≦1. 
     
     
       10. A Group III nitride compound semiconductor device according to  claim 8 , wherein each of the Group III nitride compound semiconductor layers stacked on the first surface or first and second surfaces of the substrate is formed of a compound represented by Al x Ga 1−x N, wherein 0≦x≦1. 
     
     
       11. A Group III nitride compound semiconductor device according to  claim 8 , wherein a first layer of the Group III nitride compound semiconductor layers stacked on the first surface or first and second surfaces of the substrate has a thickness of 1-20 μm. 
     
     
       12. A Group III nitride compound semiconductor device according to  claim 8 , wherein a first layer of the Group III nitride compound semiconductor layers stacked on the first surface or first and second surfaces of the substrate has a thickness of 2-10 μm. 
     
     
       13. A Group III nitride compound semiconductor device according to  claim 8 , wherein said substrate is electrically conductive. 
     
     
       14. A Group III nitride compound semiconductor device according to  claim 13 , wherein said at least one layer is a cladding layer. 
     
     
       15. A Group III nitride compound semiconductor device according to  claim 8 , wherein said at least one layer is a cladding layer.